Gun fire dead area control apparatus



W. H. SCHOFIELD GUN FIRE DEAD AREA CONTROL APPARATUS Nov. 24, 1959 3Sheets-Sh t 1 Filed y 8, 1958 IN VENTOR.

WENTWORTH H. SCHOFIELD BY )1"- s. D /1;h 4fi 2 ,1. 9140! w- #x A/M Nov.24, 1959 w. H. SCHOFIELD 2,913,961

GUN FIRE DEAD AREA CONTROL APPARATUS Filed May 8, 1958 3 Sheets-Sheet. 2

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GUN FIRE DEAD AREA CONTROL APPARATUS Filed May 8, 1958 3 Sheets-Sheet 3m a mm a; M -WM United Sates GUN FIRE DEAD AREA CONTROL APPARATUSWentworth H. Schofield, Ridgewood, NJ., assignor to the United States ofAmerica as represented by the Secretary of the Army Application May 8,1958, Serial No. 734,063

1 Claim. (CI. 89-41) (Granted under Title 35, US. Code (1952), see. 266)atent O to provide such a method and apparatus which is simple, and easyto control in a more accurate manner and in a short time.

Prior attempts at the control of such a dead area have been tried. Animportant field of use for such a control has been in connection withthe rapid changes in azimuth and elevation of an antiaircraft gunoperated automatically by remote control in tracking a rapidly movingaircraft target. Such guns are frequently located near an industrialplant or bridge or other landmark into which a shell should not befired, yet the gun is moved so rapidly that personnel at the gun cannotbe relied on to protect such areas from the fire of the gun. One suchprior suggestion has been made in the patent to P. E. Pleusse 2,692,534dated October 26, 1954, upon which the present invention is animprovement.

According to this invention, such a device has been provided with meansfor more easily and more quickly changing the outline and location ofsuch an area into which the gun cannot fire, as will be necessary when agun is moved from one location to another. More specifically, apreferred apparatus consists of a cylinder or a drum rotated in responseto changes in azimuth of the gun, and a longitudinally movable contactis responsive to changes in gun elevation. A sheet of paper is removablysecured around said drum and the outline of the safe area markedthereon. The area into which the gun may fire is coated with a silversolution to provide a conductive path for the current between thelongitudinally shiftable contact and a stationary contact through theelectrically conductive coating. When the shiftable contact reaches adead area representing the area into which the gun should not fire, thecurrent is automatically interrupted and the gun cannot fire, as theprimer circuit is interrupted.

Fig. 1 is a diagrammatic view showing the gun and means for transmittingmovements in azimuth and elevation from the gun to the apparatus.

Fig. 2 is a longitudinal section through the apparatus to which changesin elevation and azimuth of the gun are connected.

Fig. 3 is a section on the line 3-3 of Fig. 2.

Fig. 4 represents a typical map of the live and dead areas.

Fig. 5 is a less common map showing other areas.

As shown in Fig. 1, an anti-aircraft gun 10 is provided with the usualbase or bull ring 11 driving a gear 12 engaged therewith and drivingthrough the flexible connection 13 a portion of the apparatus shown inFig. 2. A gear is mounted on the trunnion or on the elevation quadrant15 driving a gear 16 and a flexible connection 17 leading to anotherpart of the apparatus in Fig. 2.

The elevation changes made by the gun are transmitted through theflexible connection 17 to a shaft on which is mounted a gear or wheel 18and thence motion is transmitted through a pair of universal connections19 and 20 to a gear 21 meshing with another gear 22 driving therotatable threaded rod 23 on which is mounted a movable contact member24. A stationary contact 25 engages a paper removably mounted on thedrum 26. The movable contact 24 is moved up and down along the threadedrod 23 with changes in gun elevation. In one embodiment of the presentinvention the paper was approximately 2% inches in height or along thedrum longitudinal axis so that as the gun pointed between 5 and thetotal movement in elevation in was confined to the 2% inches of thepaper or in other words l-=0.278 inch on paper. As shown in Fig. 2, thepaper 27 is removably mounted on the drum 26 and an enclosing housing 28surrounds the drum, the same being provided with a removable cover 29.

The flexible shaft 13 from the gun for moving the paper in rotation isshown as being transmitted to a gear driving a larger gear 30 on theshaft 30a. A gear 31 drives another gear, not shown, and eventulalydrives the gear 32 which engages a shaft on which is mounted a gear 33driving a gear 34 on the shaft of the drum, thus driving the drum. 360of rotation in azimuth by the gun and bull ring efifect a movement of360 rotation in the drum and the paper. In Fig. 3, the drum contains apaper retainer in the form of a small cylinder having a slot and mountedbeneath the surface of a slot in the large drum. The paper retainercontains a clamping pin or arm at one end by means of which thisretainer may be rotated with respect to the cylinder and clamp the paperin place. Any type of means for quickly attaching and removing the paperfrom the drum may be used.

To install a new sheet of paper as is necessary when the gun is moved toa new location, the drum is removed through the top cover 29 beingremoved, and then a new piece of paper is put in position on the drum. Asheet of carbon paper is placed around the drum over the drum paper andmay be fastened with cellophane tape to assist in marking the safe andunsafe areas. With the paper in position, the gun travels through itsfull 360 in azimuth. The azimuth and elevation limits of distantfriendly areas from the gun are determined from firing tables and mapsand the boundaries of these areas are marked. For example, if a friendlyarea is located between azimuth readings of 2350 mils and 2550 mils atelevation readings of 910 mils and 980 mils, the following procedure isused to track this area:

(1) Traverse the gun, at its minimum elevation to an azimuth heading of2350 mils (2) Elevate the gun to 980 mils (3) Traverse the gun to 2550mils (4) Depress the gun to 910 mils (S) Traverse the gun back to 2350mils at the elevation of 910 mils (6) Depress the gun to minimumelevation.

minutes the paint will have dried, when the drum may be replaced and thecover 29 put back. Friendly or safe areas are not coated with the silverwhereby the live areas representing the majority of field of fire willbe fired into tion of the paper.

the paper as shown.

as current passes between the two contacts 24 and 25 in tracking atarget.

One typical type of map or marked paper is shown in Fig. 4 in which thelive areas containing the silver coat are represented by the numeral 35and the dead or safe areas by the numeral 36. In Fig. 4, as thestationary contact engages the paper at the point 37, the movablecontact will allow firing of the gun whenever the movable contact isanywhere on a silver or conductive coated por- In Fig. 5 is representedan unusual type of map in which the silver or conductive area 35a is ofthe shape indicated surrounding the dead area 36a.

In this case, if the stationary contact reaches the position 37a in Fig.5, then in order to allow the gun to be fired by the movable contactbeing in the conductive area below the point 37a, it will be desirableto add a small border to the paper in order that conductive material maybe added along a strip extending around at least two sides of This willbe equivalent to moving the stationary contact up into the narrowconductive border above the safe area in Fig. 5 in order that the gunmay be fired when the movable contact is in the conductive area below.

It may be mentioned that this invention enables more than one safe ordead area to be possible with a live area at the same azimuth settingyet such was not possible with the apparatus of Pleusse, 2,692,534referred to above since in that construction it was possible to haveonly one live or safe area at a given azimuth setting. The presentinvention enables a sharper line to be drawn between live and dead areasthan was the case with Pleusse. For exconductive and abrasive resistanceproperties.

ample, if the object to be protected were near one edge of the dead areait would be necessary in Pleuss to have not only the inevitable 64 milsof safe area but substantially twice that amount or 128 mils. Theapparatus of the present invention is easier and quicker to make readyfor firing. The maps of Figs. 4 and 5 do not take a great deal of timeto prepare. Any quick drying conductive paint can be used, although thesilver coating 4817 described in Du Pont Bulletin CP-Z-S 51 is preferredfor its In contrast to the simplicity of the conductive map of thisinvention Pleusse had 64 contacts to be adjusted.

I claim In a system for defining a live area into which a gun may befired, the combination of a first mentioned means for moving said gun inazimuth, a second mentioned means for moving said gun in elevation, adrum, a sheet of paper removably secured around said. drum and having aconductively coated area representative of said live area means forrotating said drum with said first means, a fixed electrical contactengaging said sheet, a movable electrical contact engaging said sheet,and means for moving said movable contact with said second means.

References Cited in the file of this patent UNITED STATES PATENTS2,542,483 Fonseca Feb. 20, 1951 2,692,534 Pluess Oct. 26, 1954 FOREIGNPATENTS 583,078 Great Britain Dec. 6, 1946

